1. Technical Field
The present invention relates to a drive apparatus driven by electromagnetic force.
2. Background Art
In recent years, linear drive apparatus (linear motors) are increasingly employed as the drive source in semiconductor manufacturing equipment. A variety of structures have been proposed for such linear motors. For example, JP Patent Publication (Unexamined Application) No. 2001-28875 (to be hereafter referred to as Prior Art 1) discloses a linear motor that is of a multiphase structure using a single coil in order to facilitate production, attain reduction in size, and improve power efficiency. In this linear motor, the armature comprises cores of two kinds of shapes that are arranged in a manner such that the two shapes alternate.
(Patent Literature 1)
JP Patent Publication (Unexamined Application) No. 2001-28875 (FIG. 4).
In this example, where a plurality of armature units are connected to form a multiphase linear motor, the length of the coil becomes longer in proportion to the number of phases, thus limiting the locations where the motor can be installed.